Preparation Of Magnesium Silicate/Bentonite Microspheres By Spray Drying Method And Their Adsorption Properties

Silicate materials not only have large reserves,low economical advantages,but also have good adsorption and catalytic capabilities,and are widely used in industrial catalysis,dye decolorization,oil deacidification and refined polyether polyols.In this thesis,magnesium silicate was synthesized by precipitation method using magnesium sulfate and water glass as raw materials.The bentonite and hydroxymethyl cellulose were used as binders to study the preparation of magnesium silicate microspheres,bentonite microspheres and bentonite by spray drying method.The process technology of magnesium silicate microspheres was studied to study the effects of activation temperature and binder content on sample structure,deacidification performance and adsorption performance.(1)Magnesium silicate microsphere samples with uniform size were prepared by spray drying using magnesium sulfate and water glass as raw materials and hydroxyruethyl cellulose as binder.Magnesium silicate microsphere samples were characterized by SEM,XRD,N2 adsorption and desorption,CO2-TPD and NH3-TPD.Studies have shown that as the activation temperature increases,the number of basic and acidic sites of magnesium silicate microspheres decreases,and the specific surface area decrease.The MC-0 sample has a maximum specific surface area of 436 m2/g.The unactivated microsphere sample had the highest adsorption capacity for free fatty acids 0.307 mg/g,and the deacidification rate was 45.1%,the maximum adsorption capacity for methylene blue is 156 mg/g.(2)Bentonite purified by using sodium hexametaphosphate as a dispersing agent.Spherical and bowl-shaped bentonite particles were prepared by spray drying using hydroxymethyl cellulose as a binder.Bentonite microsphere samples were characterized by SEM and XRD.Studies have shown that with the increase of activation temperature,the specific surface area and pore volume of bentonite microspheres increase,the number of surface acid sites and basic sites decrease,and BC-8-600 has the largest specific surface area of 92.5 m2/g.Sample BC-8-600 had the largest free fatty acid adsorption capacity 0.207 mg/g and the deacidification rate was 30.5%,has the largest adsorption capacity of methylene blue 88 mg/g.(3)Using high-purity bentonite and synthetic magnesium silicate as raw materials and hydroxymethyl cellulose as binder,spheroidal bentonite-magnesium silicate particles were prepared by spray drying method.Bentonite-magnesium silicate microsphere samples were characterized by SEM,BET and other means.Studies have shown that as the activation temperature increases,the number of acidic and basic sites of bentonite/magnesium silicate microspheres decreases,and the specific surface area decrease.The sample MCB-10-400 has a maximum specific surface area of 460 m2/g.The activated sample at 400? has the largest free fatty acid adsorption capacity 0.323 mg/g,and the deacidification rate is 47.5%,The maximum adsorption capacity for methylene blue is 166 mg/g.